Ecology of Species of Bombus Latr. (Hymenoptera: Apidae) in Southern Alberta. IV. Subgenus Fervidobombus Skorikov

Abstract

AbstractTwo of the four Nearctic species of Fervidobombus occur in southern Alberta. One, Bombus californicus, is confined to the wooded areas whereas the other, B. fervidus, is confined to the prairie. When given a choice, B. fervidus nested in underground hives and B. californicus mostly in surface hives. Queens of B. fervidus sometimes made false nests at tunnel entrances. Both established nests late but were not the latest species to establish in their respective habitats.B. californicus made 10 ± 3 and B. fervidus 8 ± 1 cells in the first broods. Both constructed pollen-pockets beside and beneath the broods of young larvae destined to become workers. Queens required about 27 days to rear the first workers. The workers of succeeding broods were progressively larger, the last ones produced being almost as large as queens. B. fervidus produced more broods of workers than B. californicus; colonies of B. fervidus averaged 247 individuals, the largest being 287, whereas those of B. californicus averaged only 52, the largest being 97.Males of B. fervidus were attracted to nests containing new queens. New queens of B. californicus dug about 1.5 in. into the ground to hibernate.Females of the cuckoo bee, Psithyrus insularis, succeeded in having their young reared to maturity in nests of B. californicus. The big-headed fly, Physocephala texana, parasitized founding queens of B. fervidus.